Wow, did I ever open a can of worms. Maybe I'm going overboard pampering this rig and should just give the tranny fluid a rest (you'd probably be appalled to know that I still change the oil the old-fashioned way, every 3k miles despite the FSS, and yes it's $4/quart synthetic).
On a related note, my winter/airport car is a Taurus (the 4th I've had since 1988) and Taurus #3 spent a long while out in CO with the ex-wife before she gave it back to me (an important distinction only because it was a period of "minimal" maintenance as you might expect). When it returned to me at 100k mi, I started thinking about changing the tranny fluid--- the shop recommended against it (never having been done at all). I tried it out, and when I sold the car at 160k miles the tranny was still purring along. I wouldn't expect it to have been constructed as well as the MBZ variety and it did just fine.
Am looking forward to checking this thread again when I get back in town next week.......thanx to all for the spirited discussion!
Jeff